Kepler-80 c
Astrophysical Synthesis & Habitability Characterization
Kepler-80 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-80, located approximately 1205 light-years (369.45 parsecs) from the Solar System. First announced in 2012 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1373% across the stellar disk), this world measures 2.74 Earth radii and has a measured mass of 6.74 Earth masses. Combining its mass and radius yields a mean bulk density of 1.81 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 17.5 km/s.
In its orbital architecture around Kepler-80, Kepler-80 c completes one full revolution every 9.524 Earth days at a semi-major axis of 0.0792 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0079 (ranging from 0.0786 AU at periapsis to 0.0798 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 495 K (+222°C / +432°F) and receiving 36.48 S⊕ (~49,652 W/m²), Kepler-80 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-80 is classified as an orange K-type star of spectral type K5 with an effective photospheric temperature of 4,540 K, a radius of 0.678 R☉, a mass of 0.73 M☉, an estimated bolometric luminosity of 0.175 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-80 shines at apparent V-band magnitude 15.23 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-80 system is a multi-planet architecture hosting 6 confirmed worlds, with Kepler-80 c sharing its stellar neighborhood alongside Kepler-80 f, Kepler-80 d, Kepler-80 e, Kepler-80 b, Kepler-80 g.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-80 |
| Spectral Type | K5 |
| Effective Temp (Teff) | 4,540 K |
| Stellar Radius | 0.6780 R☉ |
| Stellar Mass | 0.7300 M☉ |
| Bolometric Luminosity | 0.175 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 15.230 · G: 14.756 |
| System Architecture | 1 Star, 6 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.079200 AU |
| Orbital Period | 9.524 days |
| Mean Orbital Velocity | 90.5 km/s |
| Orbital Eccentricity (e) | 0.00790 |
| Orbital Inclination (i) | 89.3300° |
| Mean Bulk Density | 1.81 g/cm³ (17.5 km/s vesc) |
| Insolation Flux | 36.4820 S⊕ (~49,652 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1205.000 LY (369.451 pc) |